1. Field of the Invention
The invention relates to an optoelectronic device and more particularly to an image sensor device having a sub-wavelength anti-reflection structure.
2. Description of the Related Art
As optoelectronic applications, such as digital cameras, digital video recorders, image capture capable mobile phones and monitors, become more and more popular, the demand for image sensor devices accordingly increase. An image sensor device is used for recording a photo signal change from an image and converting the photo signal into an electronic signal. After recording and processing the electronic signal, a digital image is generated. In general, image sensor devices can be categorized into two main types, one is charge coupled devices (CCD) and the other complementary metal oxide semiconductor (CMOS) devices.
The image sensor typically includes the photosensitive parts, such as photosensors, sensing the lights and accumulating photocharges and control circuit parts transforming the photocharges into electric signals and generating data. In order to increase the photosensitivity of the image sensor device, there have been proceeded endeavors to increase the fill factor of the photosensitive parts in the unit pixel. However, since the control circuit parts cannot be completely eliminated, the photosensitive parts exist in a limited area. Moreover, if the unit pixel size increases to improve the photosensitivity, the resolution will be reduced due to reduction of the number of the pixels.
Therefore, there is a need to develop a novel structure of an image sensor device capable of increasing photosensitivity of the image sensor device.